Radiation is energy that
comes from a source and travels through some material or through space. Light, heat
and sound are types of radiation. The kind of radiation discussed in this presentation is
called ionizing radiation because it can produce charged particles (ions) in matter.

Ionizing radiation is produced by unstable atoms. Unstable
atoms differ from stable atoms because they have an excess of energy or mass or both.

Unstable atoms are said to be radioactive. In order to reach
stability, these atoms give off, or emit, the excess energy or mass. These emissions are
called radiation. The kinds of radiation are electromagnetic (like light) and particulate
(i.e., mass given off with the energy of motion). Gamma radiation and
X-rays are examples of electromagnetic radiation. Beta and alpha radiation are examples of particulate radiation. Ionizing
radiation can also be produced by devices such as X-ray machines.

Radiation
exposure occurs by diagnostic X-ray. Irradiation by machine-generated radiation occurs
only when the machine is turned on.

There is also natural background radiation exposure. It
comes from cosmic rays and from naturally occurring radioactive materials contained in the
earth and in living things.

Irradiation is exposure to penetrating radiation. Irradiation occurs when all
or part of the body is exposed to radiation from an unshielded source. External
irradiation does not make a person radioactive.

Contamination occurs when material that contains radioactive
atoms is deposited on skin, clothing, or any place where is it not desired. If is
important to remember that radiation does not spread or get "on" or
"in" people; rather it is radioactive contamination that can spread. A person
contaminated with radioactive materials will be irradiated until the source of radiation
(the radioactive material) is removed.

A person is externally contaminated if radioactive
material is on skin or clothing.

A person is internally contaminated if radioactive
material is breathed in, swallowed, or absorbed through wounds.

The environment is contaminated if radioactive
material is spread about or uncontained.